Johannes Weiner
acb265a5cc
kernel: sysctl: make drop_caches write-only ...
[ Upstream commit 204cb79ad42f015312a5bbd7012d09c93d9b46fb ]
Currently, the drop_caches proc file and sysctl read back the last value
written, suggesting this is somehow a stateful setting instead of a
one-time command. Make it write-only, like e.g. compact_memory.
While mitigating a VM problem at scale in our fleet, there was confusion
about whether writing to this file will permanently switch the kernel into
a non-caching mode. This influences the decision making in a tense
situation, where tens of people are trying to fix tens of thousands of
affected machines: Do we need a rollback strategy? What are the
performance implications of operating in a non-caching state for several
days? It also caused confusion when the kernel team said we may need to
write the file several times to make sure it's effective ("But it already
reads back 3?").
Link: http://lkml.kernel.org/r/20191031221602.9375-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-01-04 19:13:17 +01:00
bpf/stackmap: Fix deadlock with rq_lock in bpf_get_stack()
2019-12-31 16:35:20 +01:00
cgroup: pids: use atomic64_t for pids->limit
2019-12-17 20:34:56 +01:00
kconfig: tinyconfig: remove stale stack protector fixups
2018-06-15 07:15:28 +09:00
kdb: Don't back trace on a cpu that didn't round up
2019-02-12 19:47:19 +01:00
dma-debug: add a schedule point in debug_dma_dump_mappings()
2020-01-04 19:12:43 +01:00
perf/core: Consistently fail fork on allocation failures
2019-12-13 08:51:04 +01:00
gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT
2018-06-08 18:56:02 +09:00
irq/matrix: Fix memory overallocation
2019-12-01 09:17:13 +01:00
livepatch: Nullify obj->mod in klp_module_coming()'s error path
2019-10-07 18:57:10 +02:00
Revert "locking/pvqspinlock: Don't wait if vCPU is preempted"
2019-10-11 18:21:06 +02:00
x86/power: Fix 'nosmt' vs hibernation triple fault during resume
2019-06-11 12:20:52 +02:00
printk: fix integer overflow in setup_log_buf()
2019-12-01 09:16:14 +01:00
rcuperf: Fix cleanup path for invalid perf_type strings
2019-05-31 06:46:30 -07:00
cpufreq: Avoid leaving stale IRQ work items during CPU offline
2019-12-31 16:36:22 +01:00
y2038: make do_gettimeofday() and get_seconds() inline
2019-11-20 18:45:24 +01:00
tracing/kprobe: Check whether the non-suffixed symbol is notrace
2019-12-31 16:36:02 +01:00
acct_on(): don't mess with freeze protection
2019-05-31 06:46:05 -07:00
kernel/async.c: revert "async: simplify lowest_in_progress()"
2018-02-06 18:32:44 -08:00
audit: use ktime_get_coarse_real_ts64() for timestamps
2018-07-17 14:45:08 -04:00
audit: track the owner of the command mutex ourselves
2018-02-23 11:22:22 -05:00
fsnotify: add fsnotify_add_inode_mark() wrappers
2018-05-18 14:58:22 +02:00
audit: Embed key into chunk
2019-12-13 08:51:11 +01:00
audit_get_nd(): don't unlock parent too early
2019-12-13 08:51:02 +01:00
audit: fix a memory leak bug
2019-05-31 06:46:17 -07:00
audit: print empty EXECVE args
2019-12-01 09:17:17 +01:00
kbuild: fix kernel/bounds.c 'W=1' warning
2018-11-13 11:08:47 -08:00
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
time: Enable get/put_compat_itimerspec64 always
2018-06-24 14:39:47 +02:00
cpu/SMT: State SMT is disabled even with nosmt and without "=force"
2019-11-24 08:20:18 +01:00
kernel/crash_core.c: print timestamp using time64_t
2018-08-22 10:52:47 -07:00
access: avoid the RCU grace period for the temporary subjective credentials
2019-07-31 07:27:11 +02:00
delayacct: Use raw_spinlocks
2018-04-27 14:34:51 +02:00
proc: introduce proc_create_single{,_data}
2018-05-16 07:23:35 +02:00
kernel/elfcore.c: include proper prototypes
2019-10-11 18:21:23 +02:00
proc: introduce proc_create_single{,_data}
2018-05-16 07:23:35 +02:00
cgroup: Call cgroup_release() before __exit_signal()
2019-08-09 17:52:34 +02:00
extable: Make init_kernel_text() global
2018-02-21 16:54:06 +01:00
bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe
2018-06-21 12:33:19 +02:00
fork: fix some -Wmissing-prototypes warnings
2019-12-05 09:21:04 +01:00
PM / reboot: Eliminate race between reboot and suspend
2018-08-06 12:35:20 +02:00
futex: Prevent robust futex exit race
2019-12-01 09:17:38 +01:00
kernel: make groups_sort calling a responsibility group_info allocators
2017-12-14 16:00:49 -08:00
kernel: hung_task.c: disable on suspend
2019-04-20 09:16:02 +02:00
memremap: split devm_memremap_pages() and memremap() infrastructure
2018-05-15 23:08:33 -07:00
irq_work: Do not raise an IPI when queueing work on the local CPU
2019-05-31 06:46:19 -07:00
jump_label: move 'asm goto' support test to Kconfig
2019-06-04 08:02:34 +02:00
kallsyms: Don't let kallsyms_lookup_size_offset() fail on retrieving the first symbol
2019-09-21 07:17:02 +02:00
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
kconfig: include kernel/Kconfig.preempt from init/Kconfig
2018-08-02 08:06:54 +09:00
kernel/kcov.c: mark write_comp_data() as notrace
2019-02-12 19:47:20 +01:00
kexec: add call to LSM hook in original kexec_load syscall
2018-07-16 12:31:57 -07:00
kexec: Allocate decrypted control pages for kdump if SME is enabled
2019-11-24 08:20:29 +01:00
treewide: Use array_size() in vzalloc()
2018-06-12 16:19:22 -07:00
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
kprobes: Blacklist symbols in arch-defined prohibited area
2019-12-05 09:20:26 +01:00
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-08-13 11:25:07 -07:00
y2038: futex: Move compat implementation into futex.c
2019-12-01 09:17:38 +01:00
mm, devm_memremap_pages: add MEMORY_DEVICE_PRIVATE support
2019-01-13 09:51:04 +01:00
modsign: log module name in the event of an error
2018-07-02 11:36:17 +02:00
kernel/module.c: wakeup processes in module_wq on module unload
2019-12-17 20:35:57 +01:00
modsign: log module name in the event of an error
2018-07-02 11:36:17 +02:00
padata: use smp_mb in padata_reorder to avoid orphaned padata jobs
2019-07-26 09:14:25 +02:00
kernel/panic.c: do not append newline to the stack protector panic string
2019-12-01 09:17:10 +01:00
kernel/params.c: downgrade warning for unsafe parameters
2018-04-11 10:28:37 -07:00
Fix failure path in alloc_pid()
2019-01-13 09:51:06 +01:00
signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sig
2019-07-26 09:14:01 +02:00
ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME
2019-07-10 09:53:41 +02:00
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
PM / reboot: Eliminate race between reboot and suspend
2018-08-06 12:35:20 +02:00
relay: check return of create_buf_file() properly
2019-03-13 14:02:35 -07:00
resource: fix locking in find_next_iomem_res()
2019-09-16 08:22:20 +02:00
rseq: uapi: Declare rseq_cs field as union, update includes
2018-07-10 22:18:52 +02:00
audit/stable-4.18 PR 20180605
2018-06-06 16:34:00 -07:00
signal: Always ignore SIGKILL and SIGSTOP sent to the global init
2019-11-20 18:46:21 +01:00
cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM
2019-02-12 19:47:25 +01:00
smpboot: Remove cpumask from the API
2018-07-03 09:20:44 +02:00
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
nohz: Fix missing tick reprogram when interrupting an inline softirq
2018-08-03 15:52:10 +02:00
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-08-13 11:25:07 -07:00
kernel/sys.c: prctl: fix false positive in validate_prctl_map()
2019-06-15 11:54:01 +02:00
Merge branch 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-06-10 10:17:09 -07:00
kernel: sysctl: make drop_caches write-only
2020-01-04 19:13:17 +01:00
staging: irda: remove remaining remants of irda code removal
2018-04-16 11:26:49 +02:00
locking/barriers: Convert users of lockless_dereference() to READ_ONCE()
2017-12-17 13:57:15 +01:00
pids: introduce find_get_task_by_vpid() helper
2018-02-06 18:32:46 -08:00
kprobes: Remove jprobe API implementation
2018-06-21 12:33:05 +02:00
torture: Keep old-school dmesg format
2018-06-25 11:30:10 -07:00
tracepoint: Fix tracepoint array element size mismatch
2018-10-17 15:35:29 -04:00
headers: untangle kmemleak.h from mm.h
2018-04-05 21:36:27 -07:00
fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown() wrappers
2018-04-02 20:15:59 +02:00
kernel: provide ksys_*() wrappers for syscalls called by kernel/uid16.c
2018-04-02 20:15:30 +02:00
umh: fix race condition
2018-06-07 16:56:28 -04:00
userns: use irqsave variant of refcount_dec_and_lock()
2018-08-22 10:52:47 -07:00
userns: also map extents in the reverse map to kernel IDs
2018-11-13 11:09:00 -08:00
uts: create "struct uts_namespace" from kmem_cache
2018-04-11 10:28:35 -07:00
sys: don't hold uts_sem while accessing userspace memory
2018-08-11 02:05:53 -05:00
watchdog: Respect watchdog cpumask on CPU hotplug
2019-04-03 06:26:29 +02:00
watchdog: Mark watchdog touch functions as notrace
2018-08-30 12:56:40 +02:00
workqueue: Fix missing kfree(rescuer) in destroy_workqueue()
2019-12-17 20:35:50 +01:00
workqueue: Set worker->desc to workqueue name by default
2018-05-18 08:47:13 -07:00
acb265a5cc